to put that work in (pronounced pu-da-wor-iyn) can mean several things. Generally speaking, it means to work at a job or get money. Another meaning of the term would be to have sex with a women. Overall, it can mean anything that improves oneself; it can be something that one does on a daily basis just to maintain sanity or health.

Example 1
#29: " I be tellin niggas...they gotta be puttin that work in. That cheese ain't gonna come on its own. If niggas want that paper, they gotta be puttin that work in"
Erup: No doubt, no doubt. I be telling my niggas that to.

Example 2
Alex: Yo Dave, where were you last night? I thought you said we was gonna chill?
Dave: Sorry bro, I was puttin that work in. I got this new bitch. She got that ass. So, anyway, what you end up doing last night?
Alex: Putting that work in with my bitch to.
Dave: Das wussup

Example 3
JLew: I'm going crazy man, and I feel like shit. I gotta put that work in.